Science does believe that a perceived gender develops in a child's brain, but as far as I know, its unclear when or how it develops. It could be before birth, or years after.
No, science does not believe that. Sociologists with questionable record regarding the validity of their studies believe that, however they do completed forget that humans are not isolated and decoupled from animals.
Males and females are vastly different and there's nothing constructed about this.
What science does know is that if your perceived gender is incongruent with your sex, it can cause gender dysphoria.
Science does not know this. It's a mainstream belief now but not backed up by good data. All we know is that transition does not remediate high suicide rates, despite greater societal acceptance of transgender in general. Some studies even show higher suicide rates after transition, however the datasets are too small and the studies are all biased on way or another. We don't know!
The way to treat it is to transition to your perceived gender.
That's one hypothesis. The other one is not to treat it and just wait because a good number of those affected by gender dysphoria turn out to be just gay and very unsure about their sexual orientation. Again: We don't know because data is insufficient.
Based on an unproven hypothesis you want people to transition despite this potentially having devastating results? I would be less sure about this, I have doubts.
You must be a parody account or on a rolling level like Borat/AliG.
Not my cup of tea, have a good day sir.